Method of Manufacturing Split Bearing Races

ABSTRACT

A method of manufacturing or forming a split bearing race for an angular contact roller bearing is provided. The method includes the steps of: A) forming a generally annular blank having a first annular portion, a second annular portion, and a third annular portion disposed between the first and second annular portions, the third annular portion having a thickness greater than the thickness of the first and second annular portions; B) machining at least one of the first, second, and third annular portions; and C) forming a first and second race member of the split bearing race by bifurcating the generally annular blank along the third annular portion. The method may also include the steps of: D) heat treating the generally annular blank after machining at least one of the first, second, and third annular portions; and E) finish machining the generally annular blank subsequent to the heat treating.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application 60/956,150, filed Aug. 16, 2007, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a method of manufacturing split bearing races for an angular contact roller bearing.

BACKGROUND OF THE INVENTION

Angular contact roller bearings include two complements of roller elements disposed between an inner and an outer bearing race. The angular contact roller bearing typically employs a split bearing race for either the inner or outer bearing race. The split bearing race includes a first race member and a second race member. The split bearing race facilitates the loading or insertion of the first and second complement of roller elements during assembly of the angular contact roller bearing. The dimensional tolerances of the first and second race members must be maintained to ensure proper functioning and reliability of the angular contact roller bearing.

SUMMARY OF THE INVENTION

A method of manufacturing or forming a split bearing race for an angular contact roller bearing is provided. The method includes the steps of: A) forming a generally annular blank having a first annular portion, a second annular portion, and a third annular portion disposed between the first and second annular portions, the third annular portion having a thickness greater than the thickness of the first and second annular portions; B) machining at least one of the first, second, and third annular portions; and C) forming a first and second race member of the split bearing race by bifurcating the generally annular blank along the third annular portion. The method may also include the steps of: D) heat treating the generally annular blank after machining at least one of the first, second, and third annular portions; and E) finish machining the generally annular blank subsequent to the heat treating. In a preferred embodiment, the generally annular blank is formed by hot rolling.

The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a portion of an angular contact roller bearing having a split bearing race formed by first and second race members;

FIG. 2 is a schematic cross sectional diagram of the first race member of FIG. 1; and

FIGS. 3 a through 3 f are schematic cross sectional illustrations of hot rolling, machining, heat treating, grinding and bifurcating a bearing race; taken together, these figures illustrate a method of manufacturing the first and second bearing race members of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like reference numbers correspond to like or similar components throughout the several views, there is shown in FIG. 1 an angular contact roller bearing, generally indicated at 10. The angular contact roller bearing 10 is mounted within a gear member 12, such as a transfer drive gear, and is retained therein by a retaining ring 14. The angular contact roller bearing 10 includes an outer bearing race 16 and an inner bearing race 18. The inner bearing race 18 is characterized as being a split bearing race; that is, the inner bearing race 18 is formed by a first race member 20 and a second race member 22. The inner bearing race 18 defines a bore 24 sufficiently configured to receive a shaft, not shown, therein. A first plurality of roller elements 26, one of which is shown in FIG. 1, is disposed between the outer bearing race 16 and the first race member 20 of the inner bearing race 18. Similarly, a second plurality of roller elements 28, one of which is shown in FIG. 1, is disposed between the outer bearing race 16 and the second race member 22 of the inner bearing race 18. The first and second plurality of roller elements 26 and 28 cooperate with the outer bearing race 16 and the inner bearing race 18 to provide load support and axial stiffness to the gear member 12.

The first and second plurality of roller elements 26 and 28 run or roll on two pairs of convergent angular pathways. The first and second race members 20 and 22 define first and second outboard pathways 30 and 32, respectively, while the outer bearing race 16 defines first and second inboard pathways 34 and 36. A first ball track 38 is the path that the center of each of the first plurality of roller elements 26 travels within the angular contact roller bearing 10. Similarly, a second ball track 40 is the path that the center of each of the second plurality of roller elements 28 travels within the angular contact roller bearing 10. The first race member 20 includes a primary face 42 and a secondary face 44, while the second race member 22 includes a primary face 46 and a secondary face 48. The primary faces 42 and 46 cooperate to provide the necessary clearances between the first and second plurality of roller elements 26 and 28, the inner bearing race 18, and the outer bearing race 16. Therefore, the dimensional tolerances of the primary faces 42 and 46 must be maintained to ensure the reliability and proper functioning of the angular contact roller bearing 10.

Referring now to FIG. 2, and with continued reference to FIG. 1, there is shown a schematic view of the first race member 20 of FIG. 1. The distance between the primary face 42 and the first ball track 38 is indicated as L₁ and the distance between the secondary face 44 and the first ball track 38 is indicated as L₂. As described hereinabove, the dimensional tolerances of distance L₁ must be maintained, while the dimensional tolerances of the distance L₂, while important, are somewhat less important than those of distance L₁. Those skilled in the art will recognize that the dimensional tolerances of the distance between the second ball track 40 and the primary face 46 of the second race member 22 should similarly be maintained to ensure proper functioning to the angular contact roller bearing 10.

Referring to FIGS. 3 a through 3 f, and with continued reference to FIGS. 1 and 2, there is schematically illustrated a method of forming the first and second race members 20 and 22 of the inner bearing race 18 of FIG. 1. FIG. 3 a illustrates the step of forming a generally annular blank 50 from a metal such as steel. In a preferred embodiment, the generally annular blank 50 will be formed by hot rolling. In the hot rolling process a billet of metal, not shown, is deformed by a roller 52 while the temperature of the metal is maintained above its recrystalization temperature. Since the generally annular blank 50 is formed by hot rolling, a near-net shape is produced, which reduces the number of subsequent processing steps and waste created therefrom. The generally annular blank 50 has a first annular portion 54, a second annular portion 56, and a third annular portion 58 disposed between the first and second annular portions 54 and 56 and centrally located on the generally annular blank 50. The first annular portion 54 has a thickness T₁ and the second annular portion 56 has a thickness T₂. In a preferred embodiment the thicknesses T₁ and T₂ are the same, but need not be. The third annular portion 58 has a thickness T₃ which is greater than the thicknesses T₁ and T₂.

Referring now to FIGS. 3 b and 3 c, the generally annular blank 50 is machined by, without limitation, turning on a lathe or grinding. Portions 60 are removed from the generally annular blank 50 to form generally annular blank 50A, shown in FIG. 3 c. Referring to FIG. 3 c, the generally annular blank 50A is subjected to heat energy, indicated at 62, and subsequent controlled cooling, such as by quenching and tempering, to heat treat the generally annular blank 50A to significantly increase the hardness and wear resistance thereof During this heat treating operation, the generally annular blank 50A may distort slightly, and, as such, a precision machining operation may be required. Referring to FIG. 3 d, a grinder 64 (only a portion of which is shown in FIG. 3 d) is employed to machine the generally annular blank 50A subsequent to the heat treating operation shown in FIG. 3 c. The grinder 64 may have multiple grinding wheels to simultaneously machine various surfaces, such as the primary faces 42 and 46 and the first and second outboard pathways 30 and 32, all of FIG. 1. This precision machining operation provides a highly-toleranced generally annular blank 50B, shown in FIG. 3 e, and establishes the relationship between the primary face 42 and the first ball track 38 as well as the relationship between the primary face 46 and the second ball track 40. Although a grinding operation is illustrated in FIG. 3 d, those skilled in the art will recognize that other precision machining operations may be employed within the scope of the claims.

Referring now to FIG. 3 e, there is shown the generally annular blank 50B. The generally annular blank 50B is parted or bifurcated along parting line 66, disposed centrally on the generally annular blank 50B, by a cutting means such as sawing, turning, etc., to produce the first and second race members 20 and 22 shown in FIG. 3 f. Referring now to FIG. 3 f, the secondary faces 44 and 48 of the respective first and second race members 20 and 22 are formed at the parting line 66 of FIG. 3 e. Consequently, the precise dimensional tolerances of the primary faces 42 and 46 relative to the respective first and second ball tracks 38 and 40 achieved during the precision machining operation of FIG. 3 d are maintained, and the dimension L2 of FIG. 2 is established. Those skilled in the art of machining will recognize that the parting operation, via sawing, turning, etc., is inherently less dimensionally accurate than the grinding operation described hereinabove with reference to FIG. 3 d.

Although the method described hereinabove was focused on forming the inner bearing race 18, the provided method is also an effective means of producing outer bearing races of the split bearing race variety. While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims. 

1. A method of manufacturing a split bearing race for an angular contact roller bearing comprising: forming a generally annular blank having a first annular portion, a second annular portion, and a third annular portion disposed between said first and second annular portions; wherein said third annular portion has a thickness greater than the thickness of said first and second annular portions; machining at least one of said first, second, and third annular portions; and forming a first race member and a second race member of the split bearing race by bifurcating said generally annular blank along said third annular portion.
 2. The method of manufacturing a split bearing race of claim 1, wherein the split bearing race is an inner bearing race.
 3. The method of manufacturing a split bearing race of claim 1, wherein forming said generally annular blank includes hot rolling.
 4. The method of manufacturing a split bearing race of claim 1, further comprising heat treating said generally annular blank after machining at least one of said first, second, and third annular portions.
 5. The method of manufacturing a split bearing race of claim 4, further comprising finish machining said generally annular blank subsequent to said heat treating.
 6. The method of manufacturing a split bearing race of claim 5, wherein said finish machining of said generally annular blank subsequent to said heat treating is performed by grinding.
 7. A method of manufacturing a split bearing race for an angular contact roller bearing comprising: forming a generally annular blank having a first annular portion, a second annular portion, and a third annular portion disposed between said first and second annular portions; wherein said third annular portion has a thickness greater than the thickness of said first and second annular portions; wherein forming said generally annular blank includes hot rolling; machining at least one of said first, second, and third annular portions; and forming a first race member and a second race member of the split bearing race by bifurcating said generally annular blank along said third annular portion.
 8. The method of manufacturing a split bearing race of claim 7, further comprising heat treating said generally annular blank after machining at least one of said first, second, and third annular portions.
 9. The method of manufacturing a split bearing race of claim 8, further comprising finish machining said generally annular blank subsequent to said heat treating.
 10. The method of manufacturing a split bearing race of claim 9, wherein said finish machining of said generally annular blank subsequent to said heat treating is performed by grinding.
 11. A method of manufacturing a split bearing race for an angular contact roller bearing comprising: forming a generally annular blank having a first annular portion, a second annular portion, and a third annular portion disposed between said first and second annular portions; wherein said third annular portion has a thickness greater than the thickness of said first and second annular portions; wherein forming said generally annular blank includes hot rolling; machining at least one of said first, second, and third annular portions; heat treating said generally annular blank after machining at least one of said first, second, and third annular portions; finish machining said generally annular blank subsequent to said heat treating by grinding said generally annular blank; and forming a first race member and a second race member of the split bearing race by bifurcating said generally annular blank along said third annular portion. 